Semiconductor devices have been packaged in a vast variety of package configurations. These include both hermetic (gas-tight) and non-hermetic (gas-permeable) packages. Prior art hermetic packages present a number of problems as the operating frequency for the device increases. Such packages, especially for power devices, normally involve a metallic can or case through the sides of which leads extend, with the leads being sealed by glass seals to the can. The chip is bonded to the base of the can and connected to the package leads by wire bonds. As part of the packaging process a lid is sealed over the top of the can to provide a hermetic seal. Such packages suffer from substantial inductance both from the wire bond leads and from the package leads which extend through the can. In order to provide a low thermal coefficient of expansion which closely matches that of the semiconductor chips, these metallic cans are normally made of Kovar.RTM. or Invar.RTM. or similar materials which are magnetic materials. The magnetic material of the can enhances the inductance of these leads.
The above identified related application presents one solution to these prior art problems in a form of a package in which the leads extend vertically through the lid of the package and in which the package may be fabricated without the use of magnetic materials. Unfortunately, the preferred embodiment of that package restricts the density with which leads may be brought through the lid of the package while maintaining a hermetic seal.
One application where a high density of leads extending through the lid of the package would be particularly desirable is in high density interconnect systems of the type disclosed in U.S. Pat. No. 4,783,695, entitled, "Multichip Integrated Circuit Packaging Configuration and Method" by C. W. Eichelberger et al., since logic and other relatively high I/O lead count devices could be packaged in a compact, hermetically sealed package prior to mounting and interconnection using a high density interconnect system of the type described in the above-identified application.
It would be desirable to have a package of the type disclosed in application Ser. No. 07/367,525 in which individual leads may be more closely spaced while still being electrically isolated from each other.